Temperature‐Sensitive Core–Shell Microgel Particles with Dense Shell

Abstract

Dichte Schale: Aus unterschiedlich temperaturempfindlichen Polymeren ließ sich ein Kern‐Schale‐Mikrogel herstellen, dessen Schale bei mittleren Temperaturen eine höhere Segmentdichte Φ aufweist als der Kern (siehe die radialen Dichteprofile: Kern rot, Schale blau). Genauere Informationen liefert die Kleinwinkel‐Neutronenbeugung. Ein neues Formfaktormodell beschreibt die bei unterschiedlichen Temperaturen erhaltenen experimentellen Streukurven.

Self-oscillating core/shell microgels: effect of a crosslinked nanoshell on autonomous oscillation of the core

“…This effect is due to core compression as a result of seeded precipitation polymerization: thus, the swelling ability of the core becomes smaller. [24][25][26][27][28] In this study, the pNIPAm shell is thicker than the pNIPMAm shell. It has been thoroughly proven that the addition of thicker shells greatly restricts core swelling.…”

“…This difference may be related to differences in salt concentrations and to the lowered VPTT of the shell due to the deswelling of the core. 28 Next, we checked the changes in hydrodynamic diameters between the reduced Ru II and the oxidized Ru III states. Figure 3 shows the temperature dependence of the hydrodynamic diameters in the reduced Ru II and oxidized Ru III states as measured by DLS.…”

“…In addition, core/shell structured microgels can exhibit multiple responsiveness and core-or shell-specific functionalities. Herein, we carried out seeded precipitation polymerization 16,[24][25][26][27][28] of N-substituted acrylamide derivatives using self-oscillating microgels as cores. The microgels obtained were characterized by dynamic light scattering.…”

Crystals, glasses and gels : synthesis and phase behavior of soft colloids

“…Due to this different growth mechanism, it is usually more difficult to have low polydispersity in precipitation polymerizations, even though exceptions exist as demonstrated in the synthesis of microgels in Chapter 4. In addition to initiators and monomers, the reaction mixtures in these free-radical polymerizations can also contain a plethora of additives such as surfactants, polymers and fluorescent dyes, which enables tailoring of particle size, [29][30][31] shape, [32][33][34][35] surface functionality [36][37][38][39][40] and labelling. [41,42] Together with the broad range of physicochemical properties of monomers applicable in these types of reactions this has led to reports describing many different colloids with interesting properties.…”

“…Solvent-swollen microgel particles composed of the thermoresponsive polymer poly(N-isopropyl acrylamide) (pNIPAM) undergo a volume phase transition when the temperature of the surrounding aqueous phase is increased above the lower critical solution temperature (LCST) or cloud point. [35,36] These particles are typically charge stabilized, such that the particle size can be adjusted with temperature, while they remain colloidally stable. This is for example used to quench systems from a liquid to glass [37][38][39] or to create superheated colloidal crystals to study melting.…”